Authorities ramped up their efforts to catch Harrington's killer after DNA evidence submitted to the FBI by the Virginia Department of Forensic Science linked the perpetrator to the suspect in a 2005 sexual assault. The FBI has released a revised sketch of the suspect in that incident -- which took place in Fairfax City, Virg. -- showing what he might look like without facial hair.

Metallica has promised a $50,000 reward for information leading to the murderer's arrest and conviction, adding to the $100,000 already pledged by the Jefferson Are Crime Stoppers.

Harrington disappeared on Oct. 17, 2009, and the following month, the Pantera T-shirt she'd been wearing the night of the Metallica show was discovered in Charlottesville. In early 2010, remains of her skeleton were found in a field in Abernarle County, Virg.

"Remember, any information, no matter how small you might think it is, could be the crucial piece investigators need to help solve this case," Hetfield says in the new PSA.

Anyone with information on the case is encouraged to call the Jefferson Area Crime Stoppers at 434-977-4000 or the Virginia State Police at 434-352-3467. Tipsters can also send email to bci-appomattox@vsp.virginia.gov.